text: This is an extremely good overview by Bob Weinberg- _URL_0_ Cancer seems to involve multiple mutations (Figure 4 in the paper) which result in a cancer cell that is tumorigenic and insensitive to normal growth controls. These mutations can be naturally caused or greatly increased by risk factors such as smoking, radiation, exposure to carcinogens, etc. Some mutations are randomly occurring, DNA replication does have an error rate (although it is very low), and would fit your statistically determined random event. It is the multiple mutations necessary for cancer to occur that makes proximal cause enter into the equation. Your chance of a cell getting its P53 gene mutated AND a mutation inactivating E-cadherin AND the other genes necessary for cancer is much more likely when you introduce a mutagen into the equation. Also your chance for these mutations to accumulate increases with age. That's why cancer is much more prevalent with increasing age.